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A series of novel renewable copolymers based on poly(ethylene succinate) (PESu) and poly(isosorbide succinate) (PISSu), with the Isosorbide (Is)/PESu molar ratio varying from 5/95 to 75/25, were synthesized in-situ and studied in this work. A sum of characterization techniques was employed here for the structural and thermo-dynamical characterization. The sophisticated technique of dielectric spectroscopy, along with proper analysis, enabled the molecular dynamics mapping of both the local and segmental types, which is presented for such materials for the first time. With increasing the Is fraction, shorter copolymeric entities were gradually formed. Based on the overall findings, the systems were found to be homogeneous, e.g., exhibiting single glass transitions, with the two polymer segments being found to be excellently distributed. The latter is indirect, although strong, evidence for the successful copolymerization. The thermal degradation mechanism for the copolymers was exhaustingly explored employing analytical pyrolysis. The systems exhibited, in general, good thermal stability, according to the thermogravimetric analysis. Confirming one of the initial scopes for the present systems, isosorbide plays here the role of hardener (PISSu) over the soft polymer (PESu), and this is reflected in the monotonic increase of the glass transition temperature, Tg, from −16 to ~56 °C. The introduction of Is results in an increase in constraints (hardening of the matrix), while there seems to be an overall densification of the polymer (decrease of the free volume). [ABSTRACT FROM AUTHOR]

Due to excellent thermal and mechanical properties, biodegradable poly(ethylene succinate) (PES) is a promising polyester in various practical fields. In this research, three novel poly(ethylene succinate-co-2-methyl succinate) (PESMS) copolyesters were synthesized from ethylene glycol, succinic acid, and 2-methyl succinic acid as the monomers, which showed the same main chain structure as PES except the presence of methyl between −OCCH2CH2CO− groups. The influence of ethylene 2-methyl succinate unit content on the crystal structure, thermal property, crystallization behavior, spherulitic morphology and crystal growth, as well as mechanical property of PESMS copolyesters was extensively investigated. The introduction of methyl significantly increased the toughness of PESMS copolyesters. For a better understanding of the structure and properties relationship, the influence of the location of methyl between −OCH2CH2O− groups introduced from diol or between −OCCH2CH2CO− groups introduced from diacid on the thermal and mechanical properties of PES based copolyesters was also compared and discussed.

A series of novel renewable copolymers based on poly(ethylene succinate) (PESu) and poly(isosorbide succinate) (PISSu), with the Isosorbide (Is)/PESu molar ratio varying from 5/95 to 75/25, were synthesized in-situ and studied in this work. A sum of characterization techniques was employed here for the structural and thermo-dynamical characterization. The sophisticated technique of dielectric spectroscopy, along with proper analysis, enabled the molecular dynamics mapping of both the local and segmental types, which is presented for such materials for the first time. With increasing the Is fraction, shorter copolymeric entities were gradually formed. Based on the overall findings, the systems were found to be homogeneous, e.g., exhibiting single glass transitions, with the two polymer segments being found to be excellently distributed. The latter is indirect, although strong, evidence for the successful copolymerization. The thermal degradation mechanism for the copolymers was exhaustingly explored employing analytical pyrolysis. The systems exhibited, in general, good thermal stability, according to the thermogravimetric analysis. Confirming one of the initial scopes for the present systems, isosorbide plays here the role of hardener (PISSu) over the soft polymer (PESu), and this is reflected in the monotonic increase of the glass transition temperature, Tg, from −16 to ~56 °C. The introduction of Is results in an increase in constraints (hardening of the matrix), while there seems to be an overall densification of the polymer (decrease of the free volume).

Fully biobased composite materials were prepared from poly(ethylene succinate) (PESu) and hemp fibers isolated from hemp agricultural wastes. Different amounts of hemp fibers were incorporated in PESu from 10% to 75%. Additionally, the effect of Joncryl ADR® 4400 (JC) as a compatibilizer was investigated. The chemical structure, thermal behavior, crystallization, mechanical properties, antioxidant activity, hydrophilicity and soil degradation of the materials were studied. Mechanical properties are initially increased up to 20–50% HF but decrease with further addition of hemp fibers. On the other hand, antioxidant activity and soil degradation increase proportionally with the HF content. Quite unexpectedly, hydrophobicity increases with the incorporation of HF probably due to the incorporation of non-cellulosic hydrophobic compounds in the polymeric matrix. Last but not least, JC effectively contributes to a higher fiber/polymeric matrix adhesion, resulting in improved properties.

The continuous depletion of natural resources coupled with plastics pollution, has prompted the scientific community to explore alternative biobased and/or biodegradable polymers. Poly(ethylene succinate) (PESu) is a promising substitute due to its high processability and controllable biodegradation rate. Meanwhile, hemp possesses interesting properties such as being lightweight, exhibiting excellent long-term mechanical stability, and having low carbon emissions, making it an ideal option for wood replacement. Thus, PESu/hemp fiber composites (with and without compatibilizer) were prepared novel sustainable materials with improved properties. The present study aims to investigate the thermal degradation of PESu/hemp fiber composites. More specifically, thermogravimetric analysis (TGA) and pyrolysis-gas chromatography/mass spectrometry (Py–GC/MS) were employed to examine the degradation mechanism and identify decomposition products. The isoconversional methods of Vyazovkin and Friedman, as well as the model free methods, provided comparable results. Samples without compatibilizer were characterized by a two-step Cn autocatalytic mechanism, while those with compatibilizer showed a triple Cn mechanism. The main thermal degradation pathway of the composites was the β-hydrogen scission of the polymeric backbone. In conclusion, this study provides information about the thermal behavior of PESu/hemp fiber composites useful for their application as alternative "wood plastic composites (WPCs)". [ABSTRACT FROM AUTHOR]

Poly(ethylene succinate) (PESu), upon crystallization with a morphology‐modulating diluent and at low degree of supercooling, forms peculiarly novel sector‐face dendritic aggregates. Delicate dissection by various microscopic techniques is used to confirm the unique differences of these two faces in the PESu dendrites. Powerful synchrotron‐source generated X‐ray microbeam analysis is performed to prove without doubt the nature of the single crystals that self‐assemble into these two sectors, respectively. Both microscopy results and 1D/2D wide‐angle X‐ray patterns collectively confirm that one sector‐face of the PESu dendrites is composed all fully flat‐on with the single‐crystal's basal face contacting the substrate and branching growth with mutual perpendicular ≈90° angle intersections; the second face is composed fully edge‐on with the prism face contacting the substrate and growth with mutual oblique 5–30° angle intersections. The growth intersection angles are also proved by the azimuthal angles in 1D and 2D X‐ray patterns. [ABSTRACT FROM AUTHOR]

The continuous depletion of natural resources coupled with plastics pollution, has prompted the scientific community to explore alternative biobased and/or biodegradable polymers. Poly(ethylene succinate) (PESu) is a promising substitute due to its high processability and controllable biodegradation rate. Meanwhile, hemp possesses interesting properties such as being lightweight, exhibiting excellent long-term mechanical stability, and having low carbon emissions, making it an ideal option for wood replacement. Thus, PESu/hemp fiber composites (with and without compatibilizer) were prepared novel sustainable materials with improved properties. The present study aims to investigate the thermal degradation of PESu/hemp fiber composites. More specifically, thermogravimetric analysis (TGA) and pyrolysis-gas chromatography/mass spectrometry (Py–GC/MS) were employed to examine the degradation mechanism and identify decomposition products. The isoconversional methods of Vyazovkin and Friedman, as well as the model free methods, provided comparable results. Samples without compatibilizer were characterized by a two-step Cn autocatalytic mechanism, while those with compatibilizer showed a triple Cn mechanism. The main thermal degradation pathway of the composites was the β-hydrogen scission of the polymeric backbone. In conclusion, this study provides information about the thermal behavior of PESu/hemp fiber composites useful for their application as alternative “wood plastic composites (WPCs)”.

Novel biodegradable branched poly(ethylene succinate) (b-PES) composites, i.e., nucleated b-PES samples, were prepared by incorporating low loadings of cyanuric acid (CA) through a solution and casting method to enhance the crystallization rate. As an efficient nucleating agent, CA could remarkably increase the nonisothermal melt crystallization peak temperature, shorten the crystallization half-time, accelerate the overall isothermal melt crystallization, and enhance the nucleation density of b-PES spherulites in the composites. Despite the addition of CA, the crystallization mechanism and crystal structure of b-PES remained unchanged. A possible epitaxial crystallization mechanism may account for the nucleation of b-PES crystals induced by CA.

The nonisothermal melt crystallization behavior of fully biodegradable poly(ethylene succinate)/cellulose nanocrystals (PES/CNC) composites with low loadings of CNC from 0.25 to 1 wt% was studied in detail in this research at different cooling rates with differential scanning calorimetry. As an efficient heterogeneous nucleating agent, CNC remarkably enhanced the melt crystallization of PES, thereby obviously increasing the crystallization rate coefficient parameters of the composites. The Ozawa method failed to analyze the melt crystallization kinetics of both neat PES and its composites. Through the methods proposed by Dobreva and Ortega, the nucleation activity of CNC and crystallization activation energy of the composites were calculated, respectively, showing the CNC loading dependence. When CNC loading was 0.5 wt%, the composite showed the highest melt crystallization peak temperature at the same cooling rate, greatest crystallization rate coefficient, strongest nucleation activity, and highest absolute crystallization activation energy at the same extent of conversion. The nucleation mechanism of PES on CNC surface was proposed; moreover, the CNC loading dependence of the crystallization of PES was further discussed through the dispersion of CNC in PES matrix study. [ABSTRACT FROM AUTHOR]

A P‐ and Zn‐containing organic/inorganic hybrid layered metal phosphonate (PPZn) as a biocompatible nucleator was incorporated into biodegradable poly(ethylene succinate) (PES) polyester to investigate the effect of the PPZn on the crystallization behavior, crystal and aggregated structure, crystal morphology and thermal stability of the PES. Two traditional inorganic nucleators (Talc and BN) were utilized for comparison with the PPZn. The PPZn exhibited markedly higher nucleation effect than the Talc and BN. The PPZn significantly enhanced the Tc and crystallization rate, and shortened the crystallization time of the PES, as confirmed by the crystallization kinetics. Hydrogen bond interaction exists between the PPZn and PES C=O group and between the PPZn and PES amorphous C–O–C group, which facilitates the uniform dispersion of the PPZn in the PES matrix. The nucleation of the PES is mainly attributed to good crystal lattice matching between the PES and PPZn. The PPZn slightly increased the thermal degradation temperature of the PES below 380 °C. © 2021 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

A linear diamides derivative-containing organic compound (TMC306) as a nucleator was incorporated into biodegradable poly (ethylene succinate) (PES) to investigate effect of TMC306 on crystallization behavior and aggregated structure of PES. Upon incorporation of TMC306 with lower weight fraction (fTMC306), crystallization temperature (Tc), crystallization rate (k) and degree of crystallinity (Xc) of PES enhanced significantly and crystallization half-time (t1/2) reduced substantially. However, Tc, k and Xc declined progressively in the presence of higher fTMC306. Based on IR results, it suggested that TMC-306 interacts with –CO group of PES and C–O–C group of PES amorphous phase via hydrogen bond. Mechanisms on nucleation of PES and dual effects of TMC306 on crystallization behavior of PES were proposed and discussed in detail.

In this study, a thorough study of the crystallization behaviors of the biodegradable polymer composites of poly(ethylene succinate) (PESu) and hexagonal boron nitride (h-BN) was carried out. We found that h-BN had a significant nucleation effect on crystallization behaviors. DSC isothermal crystallization results demonstrated that the crystallization time of the PESu/h-BN composites became shorter after adding h-BN. The rate constant k values calculated from the Avrami equation were larger for the composites, demonstrating that PESu’s crystallization rate was increased by adding h-BN. TEM and SEM images showed the well-dispersed h-BN in the PESu matrix. Optical microscopy revealed that the PESu/h-BN composites formed more and smaller spherulites than neat PESu did, which confirmed that h-BN caused the nucleation effect. H-BN also accelerated non-isothermal crystallization kinetics. We discussed the behaviors of the Mo model, which demonstrated that h-BN promoted the kinetics of non-isothermal crystallization. The XRD diffraction patterns showed that h-BN in the composites would not obviously change the crystalline structure of PESu.

Poly(ethylene succinate) (PES) is one of the most promising biodegradable and biocompatible polyesters and is widely used in different biomedical applications. However, little information is available on its solubility and precipitation properties, despite that these solution behavior properties affect its applicability. In order to systematically study these effects, biodegradable and biocompatible poly(ethylene succinate) (PES) was synthesized using ethylene glycol and succinic acid monomers with an equimolar ratio. Despite the optimized reaction temperature (T = 185 °C) of the direct condensation polymerization, relatively low molecular mass values were achieved without using a catalyst, and the Mn was adjustable with the reaction time (40–100 min) in the range of ~850 and ~1300 Da. The obtained crude products were purified by precipitation from THF (“good” solvent) with excess of methanol (“bad” solvent). The solvents for PES oligomers purification were chosen according to the calculated values of solubility parameters by different approaches (Fedors, Hoy and Hoftyzer-van Krevelen). The theta-solvent composition of the PES solution was 0.3 v/v% water and 0.7 v/v% DMSO in this binary mixture. These measurements were also allowed to determine important parameters such as the coefficients A (=0.67) and B (=3.69 × 104) from the Schulz equation, or the Kη (=8.22 × 10−2) and α (=0.52) constants from the Kuhn–Mark–Houwink equation. Hopefully, the prepared PES with different molecular weights is a promising candidate for biomedical applications and the reported data and constants are useful for other researchers who work with this promising polyester.

Abstract The effect of different polyhedral oligomeric silsesquioxanes (POSS) structures on the crystallization behavior and dynamic mechanical properties of biodegradable poly(ethylene succinate) was investigated in this work. Two kinds of POSS molecules with different structures, i.e., trisilanolisobutyl-polyhedral oligomeric silsesquioxanes (tsib-POSS) with an open cage structure and octaisobutyl-polyhedral oligomeric silsesquioxanes (oib-POSS) with a close cage structure, were separately incorporated into PES matrix at the same low loading of 1 wt%. Both types of POSS dispersed finely in the matrix, with the size of tsib-POSS aggregates being smaller than that of oib-POSS aggregates, which was in agreement with the solubility parameter difference between the two types of POSS molecules and PES matrix. The crystallization processes of PES under different conditions were accelerated by both types of POSS; moreover, oib-POSS showed stronger acceleration effect than tsib-POSS probably due to the good lattice matching between PES and oib-POSS. The crystallization mechanism and crystal structure remained unchanged for PES in the composites, despite the type of POSS. Tsib-POSS remarkably increased the storage modulus of PES, while oib-POSS slightly decreased the storage modulus of PES. Graphical abstract Image 10335 Highlights • PES/tsib-POSS and PES/oib-POSS composites were prepared. • Both tsib-POSS and oib-POSS dispersed finely in PES matrix. • Both tsib-POSS and oib-POSS accelerated the crystallization of PES. • Oib-POSS showed stronger acceleration effect than tsib-POSS. • Tsib-POSS increased the storage modulus of PES, while oib-POSS slightly decreased. [ABSTRACT FROM AUTHOR]

To adjust the structure and properties of biodegradable poly(ethylene succinate) (PES), a series of novel poly(ethylene succinate- co -2,3-butylene succinate) (2,3-PEBS) copolyesters with low contents of 2,3-butylene succinate unit (2,3-BS) were successfully synthesized in this research via a two-stage melt polycondensation. 2,3-PEBS showed the same main chain structure as PES, except that a few of two adjacent side methyl groups were randomly linked with the main chain; therefore, 2,3-PEBS may be regarded as novel PES containing two adjacent side methyl groups. The thermal parameters, crystallization behavior, and mechanical property of 2,3-PEBS copolyesters and PES were systematically studied and compared with each other. The compositions of ethylene succinate (ES) to 2,3-BS deviated significantly from the feed ratio of ethylene glycol to 2,3-butanediol (2,3-BDO) due to the low reactivity of 2,3-BDO. The results revealed that the introduction of a small amount of two adjacent side methyl groups brought an obvious variation in the thermal and mechanical properties of PES. However, 2,3-PEBS displayed the same crystallization mechanism and crystal structure as PES. Through the introduction of a few of two adjacent side methyl groups, novel PES with significantly improved mechanical properties was synthesized, which should be interesting and important for a better understanding of the structure and properties to prepare novel biodegradable polymers from a sustainable viewpoint. [Display omitted] • Poly(ethylene succinate- co -2,3-butylene succinate) (2,3-PEBS) copolymers were synthesized. • 2,3-PEBS may be regarded as novel PES containing two adjacent side methyl groups. • The elongation at break of 2,3-PEBS copolymers was remarkably improved. • 2,3-PEBS displayed the same crystallization mechanism and crystal structure as PES. [ABSTRACT FROM AUTHOR]

The thermal behavior, mechanical and rheological properties, and hydrolytic degradation of novel branched biodegradable poly(ethylene succinate) (PES) copolymers were studied in detail and compared with those of linear PES. The branched copolymers displayed the same crystal structure as the linear homopolymer. The glass transition temperature, melting point and heat of fusion of branched PES copolymers were lower than those of linear PES and further decreased gradually with an increase of side chain content. The dynamic storage modulus values of branched PES copolymers were less than that of linear PES, and also decreased with increasing side chain content. All samples behaved as non-Newtonian fluids. Furthermore, the dynamic complex viscosity, loss modulus and storage modulus exhibited a decreasing tendency with increasing side chain content at all frequency ranges studied. In addition, the hydrolytic degradation rates were slower in branched PES copolymers than in linear PES. [ABSTRACT FROM AUTHOR]

Poly(ethylene succinate) (PES), poly(butylene succinate) (PBS), and poly(hexylene succinate) (PHS), were synthesized using succinic acid and different dihydric alcohols as materials. Enzymatic degradability by cutinase of the three kinds of polyesters was studied, as well as their solid-state properties. The biodegradation behavior relied heavily on the distance between ester groups, crystallinity, and the hydrophilicity-hydrophobicity balance of polyester surfaces. The weight loss through degradation of the three kinds of polyesters with different hydroxyl monomers took place in the order PHS > PBS > PES. The degradation behavior of the polyesters before and after degradation was analyzed by scanning electron microscopy, differential scanning calorimetry, powder X-ray diffraction, Fourier transform infrared spectroscopy, gel permeation chromatography, and thermogravimetric analysis. The decrease in relative intensity at 1800-1650 estedpolyesters were degraded simultaneously. The frequencies of the crystalline and amorphous bands were almost identical before and after degradation. Thus, enzymatic degradation did not change the crystalline structure but destroyed it, and the degree of crystallinity markedly decreased. The molecular weight and polydispersity index only changed slightly. The thermal stability of the three kinds of polyesters decreased during enzymatic degradation. [ABSTRACT FROM AUTHOR]

A chemosynthetic aliphatic polyester, poly(ethylene succinate) (PESu), was degraded by a poly(3-hydroxybutyrate) (P(3HB)) depolymerase in vitro. While P(3HB) exhibited good biodegradability in all environments, PESu hardly underwent biodegradation in a marine environment. To understand the difference in environmental degradability between PESu and P(3HB), we investigated the distribution of P(3HB)- and PESu-degrading microbes in various environments. PESu-degrading microbes were never detected in marine environments. PESu-degrading bacteria isolated from various environments in this study belonged to the phyla Firmicutes and Proteobacteria. Most PESu-degrading bacterial isolates could not degrade P(3HB), suggesting that PESu was not degraded by P(3HB) depolymerase in actual environments. In addition, all bacterial isolates that were screened for P(3HB) degrading activity from various environments in this study did not degrade PESu, suggesting that PESu does not induce P(3HB) depolymerase in their bacteria and P(3HB)-degrading bacteria are not involved in biodegradation of PESu in actual environments. Taken together, these results could be related with the low biodegradability of PESu in marine environments. [ABSTRACT FROM AUTHOR]

Poly(ethylene succinate) (PES) with weight-average molecular weight above 60,000 g mol −1 was efficiently obtained by enzymatic ring opening polymerization of cyclic oligo(ethylene succinate)s c (ES) n , which in turn were prepared by lipase-catalysed cyclocondensation in solution of dimethyl succinate and ethylene glycol. The methodology was demonstrated to be also applicable to the synthesis of high molecular weight PES-copolyesters containing butylene succinate, ε-hydroxycaproate or l -lactate units with a random distribution. [ABSTRACT FROM AUTHOR]

Biodegradable poly(ethylene succinate) (PES)/poly(ethylene glycol)-polyhedral oligomeric silsesquioxanes (PEG-POSS) nanocomposites were prepared via a solution and casting method in this work. The distribution of PEG-POSS, miscibility between PES and PEG-POSS, and crystallization behavior of PES/PEG-POSS nanocomposites were fully investigated. PEG-POSS particles were homogeneously dispersed in the PES matrix. PEG-POSS was miscible with PES to some degree, because the samples displayed a single composition dependent glass transition temperature and a depression of equilibrium melting point of PES in the nanocomposites. PEG-POSS increased the chain mobility of PES, thereby improving the nonisothermal cold and melt crystallization processes, accelerating the isothermal melt crystallization rate, and increasing the spherulitic growth rate of the nanocomposites. However, the isothermal crystallization mechanism and the crystal structure of PES were not modified by PEG-POSS. PEG-POSS enhanced the crystallization behavior of PES by acting as a plasticizer. [ABSTRACT FROM AUTHOR]

Poly(ethylene succinate) (PES), poly(butylene succinate) (PBS), and poly(hexylene succinate) (PHS), were synthesized using succinic acid and different dihydric alcohols as materials. Enzymatic degradability by cutinase of the three kinds of polyesters was studied, as well as their solid-state properties. The biodegradation behavior relied heavily on the distance between ester groups, crystallinity, and the hydrophilicity-hydrophobicity balance of polyester surfaces. The weight loss through degradation of the three kinds of polyesters with different hydroxyl monomers took place in the order PHS > PBS > PES. The degradation behavior of the polyesters before and after degradation was analyzed by scanning electron microscopy, differential scanning calorimetry, powder X-ray diffraction, Fourier transform infrared spectroscopy, gel permeation chromatography, and thermogravimetric analysis. The decrease in relative intensity at 1800–1650 estedpolyesters were degraded simultaneously. The frequencies of the crystalline and amorphous bands were almost identical before and after degradation. Thus, enzymatic degradation did not change the crystalline structure but destroyed it, and the degree of crystallinity markedly decreased. The molecular weight and polydispersity index only changed slightly. The thermal stability of the three kinds of polyesters decreased during enzymatic degradation.

Poly(ethylene succinate) (PES) with high chain regularity was synthesized by adding oxalic acid in the melt poly-condensation system. The molar ratios of diethylene glycol succinate (DEGS) units in the polymer chains were diminished from 3.8% to 0.6% when 17 mol% oxalic acid was added. Oxalic acid underwent esterification with ethylene glycol and decarboxylation, producing ethylene glycol monoformate and formate end-capped PES oligomers. The formate endcapping supressed the etherification side reactions. Ethylene glycol formate with a lower boiling point was more easily released by-production than ethylene glycol during the transesterification stage, resulting in a faster transesterification rate. Meanwhile, the molecular weights significantly increased. The high chain regularity endowed the PES with higher melting temperatures of 105 °C and remarkably increased crystallization rates. The mechanical properties, including tensile strength at break, were simultaneously improved for a high-molecular-weight PES sample (M w = 100 kg/mol). [Display omitted] • Poly(ethylene succinate) (PES) with diethylene glycol succinate (DEGS) units molar ratio as low as 0.6% has been synthesized. • The decrease of DEGS content endows PES rapid crystallization rates and high melting temperatures of 105 °C. • The molecular weight of PES was also increased, and realized improved tensile strength and elongation at break. • The mechanism of decrease DEGS content by adding oxalic acid was disclosed. [ABSTRACT FROM AUTHOR]

The effects of gamma-ray irradiation on the isothermal crystallization of biodegradable poly(ethylene succinate) (PESu) and the growth behavior of PESu spherulites have been studied by differential scanning calorimetry and polarized optical microscopy. The irradiation doses used in the study are 0, 200, 400, and 600 kGy. The kinetic parameters for the isothermal crystallization have been determined, using the Avrami relationship. The nucleation constants and activation energy for the growth of the PESu spherulites have been analyzed, using the Lauritzen-Hoffman growth theory. Triple melting points have been observed for all the irradiated PESu. The gamma irradiation has no observable effect on the Avrami exponent, and the composite rate constant increases first with the increase of the crystallization temperature, reaches maximum at the crystallization temperature of ~35 °C, and then decreases with the increase of the crystallization temperature for both the non-irradiated and irradiated PESu. There exists a transition of the growth of the PESu spherulites from regime II to regime III. Both the nucleation constants and activation energy increase with increasing the irradiation dose. The gamma irradiation increases the energy barrier for the migration of polymer chains. [ABSTRACT FROM AUTHOR]

In this work, two series of biodegradable nanocomposites of poly(ethylene succinate) (PESu) containing either graphene oxide (GO) or organomodified GO (org-GO) with 1-dodecylamine have been prepared and studied. GO was synthesized using a modified Staudenmaier method from of powdered graphite and PESu/GO and PESu/org-GO nanocomposites with GO or org-GO concentrations 0.5, 1 or 2.5 wt% were prepared with the solvent evaporation method. The nanocomposites were characterized with several techniques. Microscopic and XRD study showed intercalated dispersion of GO into PESu matrix while in the case of org-GO fully exfoliated nanocomposites were obtained. Isothermal and nonisothermal crystallization was studied from the melt or from the glass state by using DSC and it was found that nanocomposites crystallized faster than the neat PESu under both conditions. Crystallization rates increased with increasing filler content and it seems that GO have higher crystallisation effect than org-GO. This is due to the stronger interactions that are taking place between PESu and GO, as was confirmed by FTIR and DSC. In the case of the nanocomposites interesting crystalline morphologies and different to those for neat PESu were observed with PLM. Enzymatic hydrolysis studies revealed that nanocomposites have higher hydrolysis rates than neat PESu, while GO accelerates in higher extent the hydrolysis of PESu than org-GO. [ABSTRACT FROM AUTHOR]

Biodegradable poly(ethylene succinate- co -diethylene succinate) (P(ES- co -DEGS)) copolyesters with different diethylene glycol succinate (DEGS) compositions and the homopolymer poly(ethylene succinate) (PES) were successfully synthesized by a two-stage melt polycondensation method. The crystal structures, basic thermal properties, crystallization kinetics, and spherulitic morphologies of P(ES- co -DEGS) and PES were extensively investigated. Relative to PES, the glass transition temperature values of the copolyesters are slightly reduced, while their melting temperature and equilibrium melting temperature values obviously become smaller. The crystal structures of the copolyesters are the same as PES, while their degree of crystallinity values are slightly reduced. Relative to PES, the crystallization rates of the copolyesters become smaller, while the crystallization mechanisms remain almost unchanged. The morphology study revealed that the enhanced spherulite size and lowered nucleation density were observed with increasing crystallization temperature for all of the samples. [ABSTRACT FROM AUTHOR]

Conformational characteristics and configurational properties of synthetic biodegradable polyesters, poly(ethylene succinate) and poly(butylene succinate), have been investigated by NMR experiments and molecular orbital calculations on their model compounds and the rotational isomeric state calculations for the two aliphatic polyesters. The results have been related to their crystal structures and thermal properties and compared with those obtained previously for poly(( R )-3-hydroxybutyrate) and poly(lactic acid) to elucidate structure–property relationships of the representative biodegradable polyesters. In addition, selective affinities to degradative enzymes of the four polyesters have been satisfactorily explained in terms of their conformational characteristics and interactions with the depolymerases. [ABSTRACT FROM AUTHOR]

Biobased poly(ethylene succinate)- b -poly(triethylene terephthalate) (PES -b- PTEGT) multiblock copolyesters with low weight ratios of PTEGT segment were successfully synthesized from dihydroxyl terminated PES and dihydroxyl terminated PTEGT prepolymers in this work through a chain extension reaction. The thermal, crystallization, and mechanical properties of PES -b- PTEGT were systematically investigated and compared with those of PES also prepared via the chain extension method. Two glass transition temperature (T g) values were detected for PES -b- PTEGT, corresponding to the T g of PES segment and that of PTEGT segment, respectively. PES -b- PTEGT showed a high melting temperature of around 100 °C and a thermal decomposition temperature of above 320 °C. The crystallizability of PES segment in PES -b- PTEGT was obviously enhanced under different crystallization conditions, which was attributed to the interface-assisted crystallization. In addition, the mechanical property (including both the elongation at break and the tensile strength) of PES -b- PTEGT was also remarkably improved. The synthesis of PES -b- PTEGT with a high melting temperature, faster crystallization rate, and improved mechanical property provided a new modification method to improve the physical property and extend the practical application of biodegradable polyesters. [Display omitted] • Biobased PES -b- PTEGT copolyesters were synthesized via a chain extension reaction. • PES -b- PTEGT showed a high T m of around 100 °C and a T d of above 320 °C. • The crystallizability of PES segment in PES -b- PTEGT was obviously enhanced. • The mechanical property of PES -b- PTEGT was also remarkably improved. • This research proposed a novel method to modify the physical properties of PES. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hyperthermostable quaternary ammonium monomers are designed and synthesized. • In-reactor engineering of antibacterial polyesters in a large scale is provided. • The functional polyester in this work is absent from any catalyst. • The resultant polyester exhibits strong and persistent antibacterial activity. It will be a significant advance if polyesters exhibit intrinsically antibacterial property considering their wide usage in the biomedical field, non-woven fabrics and food storage. Given the poor durability and low efficiency of physically blending or post-modification with antibacterial agents, melt polycondensation using polymerizable antibacterial agents as comonomer is potentially the most versatile and efficient approach for large scale production of polyesters with intrinsic antibacterial property. However, organic antibacterial agent fails to be used as comonomer for melt polycondensation due to its poor thermal property. Herein, a facile and green strategy is proposed for the synthesis of quaternary ammonium monomers via the reaction between sodium 5-sulfoisophthalic acid and various quaternary ammoniums in water, producing a series of antibacterial monomers with the highest thermal degradation temperature up to 361 °C. Finally, antibacterial poly(ethylene succinate) (PES) was synthesized via catalyst-free melt polycondensation from ethylene glycol and succinic acid using 1-hexadecyl-3-methylimidazolium 5-sulfoisophthalic acid as comonomer. The resultant functionalized PESs exhibit comparable physiochemical properties to pure PES, with additional superior and persistent antibacterial activity. This work provides a feasible strategy for the large scale production of antibacterial polyesters through in-reactor engineering. [ABSTRACT FROM AUTHOR]

Poly(ethylene succinate) (PESu) blend with amorphous poly(vinyl phenol) (PVPh) in thin films were investigated on the crystalline spherulites patterns and crystalline lamellar arrangements by using polarized optical microscopic (POM) and atomic-force microscopy (AFM). A total of nine different types of crystalline morphology were identified in the PESu/PVPh blend with amorphous contents from 10 to 35 wt.% and T = 40-70 °C in ultra-thin film thickness. Multiple types of PESu crystalline morphology at the same crystallization temperature ( T) are never seen in neat PESu, but only occur in PESu/PVPh blend with amorphous PVPh higher than 20 wt.%. Crystalline morphology diagrams are summarized to display various spherulite types in the PESu/PVPh blend confined in thin films as a function of crystallization temperature and blend composition. Crystallization temperature, thickness/space confinement, and presence of interacting amorphous PVPh are the main factors for multiple types of spherulites in the blends, partly due to strong interactions via hydrogen bonding between PESu and PVPh and likely extra nucleation capacity from the diffusion interfaces. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

ABSTRACT In this study, poly(ethylene succinate)(PES)/graphene nanocomposites were facilely prepared by in situ melt polycondensation of succinic acid and ethylene glycol in which contained well dispersed graphene oxide (GO). Fourier transform infrared (FTIR), GPC, TGA, and XRD were used to characterize the composites. The FTIR spectra and TGA measurement confirmed that PES chains had been successfully grafted onto GO sheets along with the thermal reduction of GO to graphene during the polymerization. GPC results indicated that increasing amounts of graphene caused a slight decrease in number average molecular weight of PES matrix when polymerization time was kept constant. The content of grafted PES chains on graphene sheets was also determined by TGA and was to be about 60%, which made the graphene sheets homogeneously dispersed in the PES matrix, as demonstrated by SEM and XRD investigations. Furthermore, the incorporation of thermally reduced graphene improved the thermal stability and mechanical properties of the composites significantly. With the addition of 0.5 wt % graphene, onset decomposition temperature of the composite was increased by 12°C, and a 45% improvement in tensile strength and 60% in elongation at break were also achieved. The enhanced performance of the composites is mainly attributed to the uniform dispersion of graphene in the polymer matrix and the improved interfacial interactions between both components. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3212-3220, 2013 [ABSTRACT FROM AUTHOR]

An investigation on the crystallization of composites based on poly(ethylene succinate) and unmodified single-walled carbon nanotube was made in this report. Both isothermal and non-isothermal modes were studied along with subsequent melting behavior using differential scanning calorimetry. Crystal morphology was then explored using X-ray scattering and infrared spectroscopy. It was observed during isothermal crystallization that carbon nanotube (CNT) could contribute to the crystallization rate through heterogeneous nucleation. Furthermore, nanotubes enhanced the crystallinity within low and high undercooling rather than medium undercooling. Similar findings were obtained in non-isothermal crystallization mode. At lower cooling rates, the crystallization rate was more strongly influenced by the nanotubes, while at higher cooling rates the crystallinity was affected to the greater extent. The onset of the cold crystallization of polymer remained unaffected in presence of the nanotube, while its extent was reduced. X-ray diffraction together with infrared spectroscopy found that the polymer crystalline morphology was of α type, and no transition from α to β occurred in presence of the CNT. [ABSTRACT FROM AUTHOR]

Abstract: The crystalline structure evolution of poly(ethylene succinate) during tensile deformation was investigated by in-situ synchrotron X-ray scattering. Crystal phase transition from α to β form was confirmed to be fully reversible upon stress loading and unloading. An increase of long period was observed during the α–β crystal transition, which was attributed to the increase of both amorphous layer thickness and crystalline layer thickness (lamellar thickness). The crystalline layer thickness was scaled with the fraction of β crystal, and the change of which was in well agreement with the difference in the repeating length along the crystallographic c axis. Both the crystalline layer thickness and the amorphous layer thickness were fully recoverable. A possible molecular model was proposed to visualize the mechanism for the crystal transition and lamellar thickening. [Copyright &y& Elsevier]

Molecular weight regulated release profile and polyester enhanced aqueous stability of poorly water-soluble Nimodipine drug. [Display omitted] • Biocompatible and biodegradable polyester was synthesized by direct polycondensation. • Nanoprecipitation encapsulation of Nimodipine within poly (ethylene succinate) PES. • The encapsulated form showed a decrease of crystallinity and particle size of the drug. • Encapsulation within the polyester improved the drug's water solubility and stability. • Adjusting the drug-releasing via the variation of the molecular weight of the polyester. In the present study, we demonstrate that well-known molecular weight-dependent solubility properties of a polymer can also be used in the field of controlled drug delivery. To prove this, poly(ethylene succinate) (PES) polyesters with polycondensation time regulated molecular weights were synthesized via catalyst-free direct polymerization in an equimolar ratio of ethylene glycol and succinic acid monomers at 185 °C. DSC and contact angle measurements revealed that increasing the molecular weight (M w , 4.3–5.05 kDa) through the polymerization time (40–80 min) increased the thermal stability (T m = ∼61–80 °C) and slightly the hydrophobicity (Θ w = ∼27–41°) of the obtained aliphatic polyester. Next, this biodegradable polymer was used for the encapsulation of Ca2+ channel blocker Nimodipine (NIMO) to overcome the poor water solubility and enhance the bioavailability of the drug. The drug/ polymer compatibility was proved by the means of solubility (δ) and Flory-Huggins interaction (miscibility) parameters (χ). The nanoprecipitation encapsulation of NIMO into PES with increasing M w resulted in the formation of spherical 270 ± 103 nm NIMO-loaded PES nanoparticles (NPs). Furthermore, based on the XRD measurements, the encapsulated form of NIMO-loaded PES NPs showed lower drug crystallinity, which enhanced not only the water solubility but even the water stability of the NIMO in an aqueous medium. The in-vitro drug release experiments demonstrated that the release of NIMO drug could be accelerated or even prolonged by the molecular weights of PES as well. Due to the low crystallinity of PES polyester and low particle size of the encapsulated NIMO drug led to enhance solubility and releasing process of NIMO from PES with lower M w (4.3 kDa and 4.5 kDa) compared to pure crystalline NIMO. However, further increasing the molecular weight (5.05 kDa) was already reduced the amount of drug release that provides the prolonged therapeutic effect and enhances the bioavailability of the NIMO drug. [ABSTRACT FROM AUTHOR]